1. Field of the Invention
This invention relates to a method of treating exhaust gas, and more particularly relates to a method of treating exhaust gas, which is exhausted from an incinerator of an incineration plant provided with an incinerator and a dust collector and contains poisonous organic chlorine compounds, such as polychlorinated dibenzo-p-dioxin, polychlorinated dibenzofuran and the like, with a catalyst to decompose and remove the poisonous organic chlorine compounds in the treatment of a waste product containing a chlorine-containing polymer by the incineration plant.
2. Related Art Statement
Exhaust gas, which is generated from an incineration plant used for treating an industrial waste product or city waste product, contains poisonous substances such as SO.sub.x, NO.sub.x, HCl , cyanogen and the like, and the techniques for removing these poisonous substances have been investigated. These poisonous substances have been actually removed from the viewpoint of the protections of human body and environment. However, the investigation of the method for removing poisonous organic chloride compounds, such as dioxin, PCB, chlorophenol and the like, which are contained in exhaust gas in a very small amount, has recently been started, and a practically applicable method for removing the poisonous organic chlorine compounds has not yet been established. Among these poisonous organic chlorine compounds, a compound called dioxin is polychlorinated dibenzo-p-dioxin, which includes a dichloro-compound, tetrachloro-compound, pentachloro-compound, hexachloro-compound and the like corresponding to the number of chlorine atoms, and has a large number of isomers of more than 70. Particularly, tetrachlorodibenzo-p-dioxin (hereinafter, abbreviated as T.sub.4 CDD) is known as a substance having the strongest poisonous property. Moreover, dioxin is very stable, does not dissolve in water and has a poisonous property which does not disappear semipermanently. Therefore, dioxin has a very high influence upon the environment due to the strong and everlasting poisonous property.
The mechanism of the formation of dioxin in an incineration plant is believed to be that dioxin is formed as a by-product when a waste product containing a chlorine-containing polymer is heated and decomposed in an incinerator. However, the mechanism has not yet been fully clarified.
The object of the present invention is to provide a method of treating a waste product capable of preventing the generation of poisonous organic chlorine compounds, such as dioxin and the like, in the incineration treatment of various waste products.